Lord Norman Foster is reputed to be a cold technocrat. The modernist architect behind HSBC’s Hong Kong building and Swiss Re’s “Gherkin” uses glass and steel, his interiors are often white. Profiles refer to his “bullet head” and portray him as inscrutable. The only architect in last year’s Sunday Times Rich List, he is renowned for being fiercely driven, having created a corporate machine unusual in an industry so vulnerable to recession and strewn with bankruptcies.

Lord Foster’s grip on the international brand he has forged over four decades since founding Foster + Partners in 1967 is tight – so much so that he even insists that the typeface on all his buildings’ signage and company reports is also used in books published about him. And his reputation as an interviewee is poor; he is said to know what he is going to say before he has been asked.

So it is a surprise to discover, when meeting him at his riverside London headquarters, that he is rather personable. The 75-year-old architect, dressed in a light-blue gingham shirt with a pink trim, speaks softly and appears relaxed, occasionally leaning so far back into his chair that he is almost lying down.